Electronic Techniques for Analyzing Color Separation Errors.

An ideal color separation process is one which would provide an exact colorimetric match of the original scene. Thus, if X Y Z represent the tristimulus values of an original scene and X1 Y1 Z1 1 represent the tristimulus values of the separations then exact reproduction implies that: 1) X1 = X, Y1 = Y, Z1 = Z It has been shown that a satisfactory reproduction will be achieved if the tristimulus values of the reproduction are linear transformations of the tristimulus values of the original scene, that is, 2) X1 = kX, Y1 = kY, Z1 = kZ Errors which are introduced by the filter-emulsion-illumination system can be predicted if the transformation coefficients can be determined. This paper presents a technique for determining the errors introduced through the tricolor-filter system. The technique utilizes analogue computer techniques. Transmission values of color samples obtained from the photographic separations are introduced into an analogue computer solving the Neugebauer equations. Resulting tristimulus values can then be determined in a matter of a few seconds for each color area throughout the color gamut. This paper will present the results of applying computer techniques to the analysis of errors for representative tristimulus filter systems now being utilized for color reproduction. In particular, errors introduced through A, Band C5 filters will be compared with a system incorporating K, N, and C4 filters.